Miniatura

Quantum collective excitations in correlated electron systems: Theory meets experiment

 

Principal Investigator: dr Maciej Fidrysiak

Project duration: 2022-2023

e-mail: maciej.fidrysiak[at]uj.edu.pl

 

 

 

Quantum strongly-correlated electron systems constitute a dynamically developing area of condensed matter physics, both in the context of basic research and technological applications. Among the most prominent of them are high-temperature copper-oxide superconductors, evolving as a function of doping from the antiferromagnetic insulating state, thorough the high-temperature superconducting dome, to the correlated metal phase. Recent developments in experimental techniques, particularly in resonant inelastic x-ray scattering (RIXS), allow for detailed mapping of quantum collective excitations (plasmons, paramagnons) in those and related compounds. Since the mechanism of high-temperature superconductivity is still not fully understood, new experimental data revived the discussion of the role the fluctuations might play in superconducting pairing.

At the Jagiellonian University, we have developed an original theoretical approach to quantum fluctuations in strongly-correlated electron systems, VWF+1/N. The latter combines variational wave function (VWF) method with field-theoretical expansion in the inverse number of fermionic flavors (1/N). This scheme is now implemented as a Quantum simulation Library (QSL) and has been tested against other techniques, including determinant quantum Monte-Carlo. The aim of the present project is to study collective excitations in selected cuprate and nickelate superconductors in collaboration with experimental RIXS group from Politecnico di Milano.